Ah yeah getting all those masks is pretty fun.
The daedric quests are fun, too. I didn't like that some of them had level requirements tho, because it meant I had to play for longer than I wanted.
I really only enjoy my first playthrough of Elder Scrolls and Fallout games.
I'm definitely into the huge open worlds, where you can come over the crest of a mountain, see a little shack or small village in the distance and say "I want to go to there," or "I wonder what the story is here."
It's the same with NPCs and such.
I tend to explore and see every thing I possibly can in my first playthrough as well, which makes every other playthrough stale.